Kidnap of rising graduate on Tube (6)
I believe the answer is:
abduct
'kidnap' is the definition.
('abduct' can be a synonym of 'kidnap')
'rising graduate on tube' is the wordplay.
'rising' says the letters should be written backwards (going up in a down clue).
'graduate' becomes 'ba'.
'on' means one lot of letters go next to another.
'tube' becomes 'duct' (I've seen this before).
'ba' backwards is 'ab'.
'ab'+'duct'='ABDUCT'
'of' acts as a link.
(Other definitions for abduct that I've seen before include "Kidnap, make off with" , "Criminally remove to an undisclosed location" , "Take (someone) away by force" , "Remove by force" , "Kidnap, shanghai" .)